1. Field of the Invention
The present invention relates to antennas for multiple-input multiple-output (MIMO) wireless communications, particularly of the microstrip antenna type used, e.g., in handsets for mobile or cellular telephones, and more particularly to a high isolation multiband MIMO antenna system.
2. Description of the Related Art
The next generation of wireless systems will be capable of providing high throughputs, broader bandwidths, and better interference mitigation, thus providing multimedia services with peak data rates of more than 150 Mbps in the downlink and 50 Mbps in the uplinks. One of the key enabling technologies in such systems is the utilization of multiple-input-multiple-output (MIMO) antenna systems.
MIMO antenna systems have a group of antennas in the transmitter and receiver terminals of the wireless system. This will allow the communication system to achieve higher data rates, and thus provide better multimedia service. One of the major design challenges in MIMO antenna system design is its miniaturization and integration issues, especially in the small form factor user terminals (or handheld devices). Also, when integrating several antennas in a small area, the coupling between them increases, their diversity performance decreases, and thus the efficiency of the wireless communication system decreases so that high data rates are no longer achievable.
The new cellular and wireless systems are leaning towards the lower frequency bands of operation because of the extended coverage area and better in-building penetration of the electromagnetic waves. The antenna design for lower operating bands is a challenge by itself, since the antenna size is expected to be larger in size than the ones used in higher frequency bands (a fundamental law in electromagnetic theory).
Thus, a multiband multiple-input and multiple-output (MIMO) antenna system with improved isolation solving the aforementioned problems is desired.